Surface cleaning apparatus employing cleaning and adhesive rollers is known. Such apparatus operates by providing a cleaning roller with a surface of relatively low adhesiveness that contacts an adhesive roller of relatively high adhesiveness, the respective rollers being arranged parallel to one another and contacting each other over at least part of their length. As a web or sheet material (hereinafter referred to as a work piece) is conveyed over the surface of the cleaning roller, particulate material is removed. In order that the cleaning roller remains effective over a period of time, the removed particulate material is transferred to, and retained by, the adhesive roller during rotation of the respective rollers. Commonly, the work piece to be cleaned is conveyed through the nip of at least two opposed cleaning rollers which simultaneously remove particulate material from its opposing surfaces.
An important factor in improving production line efficiency is the minimising of downtime. A feature of surface cleaning apparatus of the type described above is that periodic removal of the cleaning and adhesive rollers is necessary. For example, the adhesive rollers need to be refreshed in order to remove saturated exterior adhesive layers and expose underlying fresh areas of adhesive.
A particular problem arises when there is localised heavy saturation of the adhesive roller around its circumference. Such problems are particularly prevalent when cleaning the trimmed edge or edges of a work piece. In doing so, the excess particulate material along the edges of the work piece tends to accumulate in a linear fashion around the circumference of the adhesive roller. The resulting non-uniform distribution of particulate material along the adhesive roller's width reduces its overall cleaning efficiency and necessitates its premature replacement. The accumulation of particulate material arises because: (i) both the cleaning and adhesive rollers extend beyond the lateral edge or edges of the work piece; and (ii) each lateral edge continuously and repetitiously contacts the cleaning roller along the same line of contact which is then transferred to the adhesive roller.
An oscillating adhesive roller is disclosed in WO2007012884. This invention allows the build up of particulate material to be dispersed over a wider area, increasing the life of the adhesive roller significantly and reducing production downtime. The arrangement of WO2007012884 requires that a roller has a cavity within it large enough to act as a reservoir to generate the required build up of pressure for movement of the piston in both directions. As such, it is ineffective with smaller rollers. Furthermore, relatively complex bespoke parts are contained within the roller of WO2007012884 which increases cost.
Standard pneumatic components are small enough to fit within most rollers but, if a roller has to oscillate or rotate, supplying the pneumatic components with a suitable air supply which allows quick and easy removal of the roller has been a problem.